Described in DE, A1, 3635873 is a two-stroke internal combustion engine with slot-type gas distribution and crankcase scavenging, comprising a crankcase with a single-throw shaft installed therein, and cylinders connected to the crankcase, each of the cylinders enclosing a piston with a pin connected to the shaft through a connecting rod, and each of the cylinders having exhaust ports communicating with an exhaust pipe, and scavenging ports communicating with a crank chamber through scavenging ports.
The problems with the prior art engine include its low fuel efficiency due to the fact that a fresh charge is emitted from the cylinder into the exhaust pipe during scavenging, and the overheating of exhaust port edges, the piston and the other working surfaces. These reasons prevent tuning the engine for the average efficient pressure.
Another conventional two-stroke engine with a slot-type scavenging comprises a crankcase with a single-throw shaft installed therein, and a cylinder connected to the crankcase and enclosing a piston with a pin connected to the shaft through a connecting rod, the cylinder having a scavenging port in communication with an inlet pipe, and an inlet/outlet port connected to an inlet/outlet passage, and a slide valve mounted within the inlet/outlet passage so that alternatively connect the passage with the inlet pipe and the exhaust pipe (SU, A1, 56419).
The above prior art overcomes many of the problems inherent in the operation process of the two-stroke engines, in particular: as compared to the previously mentioned prior art, the fresh charge emission from the cylinder during the scavenging is notably reduced owing to sealing the inlet/outlet passage by the slide valve; the cylinder charging is increased; and the temperature stress on the edges of the inlet/outlet port and a portion of the piston surface is reduced owing to cooling by fresh charge admitted through the slide valve, the inlet/outlet passage and the inlet/outlet port. However, the prior art engine fails to take full advantage of the significant prospects of improving the time-to-section of the inlet and exhaust parts.
US, A1, 5081961 (FIGS. 4.1-4.5) describes an internal combustion engine with slot-type gas distribution, comprising a crankcase with a single-throw shaft installed therein, a cylinder connected to the crankcase and enclosing a piston with a pin connected to the shaft through a connecting rod, the cylinder having two opposite inlet/outlet ports, each of the ports being connected with one of inlet/outlet passages, and each of the inlet/outlet passages having a rotary valve adapted to alternately connect the passage with an inlet and outlet pipes.
As compared to SU, A1,6419, this prior art engine provides the increased time-to-section ratio owing to the doubled number of slide valves, however, it fails to take full advantage of the possibility of increasing the time-to-section ratio; the variable volume of the crank chamber is not used as a receiver, and the compression chamber is not used for cooling and lubrication of the conversion mechanism in order to enhance the reliability of the engine firing and to cool the piston and the cylinder wall by a fresh charge. Taken together, the factors above prohibit the attainment of the highest specific characteristics in the piston engines.